Update libjava/sysdep/m68k/locks.h with new atomic builtins

Update libjava/sysdep/m68k/locks.h with new atomic builtins

[Andreas Schwab]

There is not much to gain, the builtin generates pretty much the same
code.  Tested on m68k-linux and checked in.

Andreas.

	* sysdep/m68k/locks.h (compare_and_swap): Use
	__sync_bool_compare_and_swap.
	(release_set): Use write_barrier instead of inlining it.

diff --git a/libjava/sysdep/m68k/locks.h b/libjava/sysdep/m68k/locks.h
index d70757a..b51e314 100644
--- a/libjava/sysdep/m68k/locks.h
+++ b/libjava/sysdep/m68k/locks.h
@@ -1,6 +1,6 @@
 // locks.h - Thread synchronization primitives. m68k implementation.
 
-/* Copyright (C) 2006  Free Software Foundation
+/* Copyright (C) 2006, 2012  Free Software Foundation
 
    This file is part of libgcj.
 
@@ -22,12 +22,24 @@ static inline bool
 compare_and_swap(volatile obj_addr_t *addr,
 		 obj_addr_t old, obj_addr_t new_val)
 {
-  char result;
-  __asm__ __volatile__("cas.l %2,%3,%0; seq %1"
-	      	: "+m" (*addr), "=d" (result), "+d" (old)
-		: "d" (new_val)
-		: "memory");
-  return (bool) result;
+  return __sync_bool_compare_and_swap (addr, old, new_val);
+}
+
+// Ensure that subsequent instructions do not execute on stale
+// data that was loaded from memory before the barrier.
+// On m68k, the hardware ensures that reads are properly ordered.
+static inline void
+read_barrier(void)
+{
+}
+
+// Ensure that prior stores to memory are completed with respect to other
+// processors.
+static inline void
+write_barrier(void)
+{
+  // m68k does not reorder writes. We just need to ensure that gcc also doesn't.
+  __asm__ __volatile__(" " : : : "memory");
 }
 
 // Set *addr to new_val with release semantics, i.e. making sure
@@ -38,8 +50,8 @@ compare_and_swap(volatile obj_addr_t *addr,
 static inline void
 release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
 {
-  __asm__ __volatile__(" " : : : "memory");
-  *(addr) = new_val;
+  write_barrier ();
+  *addr = new_val;
 }
 
 // Compare_and_swap with release semantics instead of acquire semantics.
@@ -53,20 +65,4 @@ compare_and_swap_release(volatile obj_addr_t *addr,
   return compare_and_swap(addr, old, new_val);
 }
 
-// Ensure that subsequent instructions do not execute on stale
-// data that was loaded from memory before the barrier.
-// On m68k, the hardware ensures that reads are properly ordered.
-static inline void
-read_barrier(void)
-{
-}
-
-// Ensure that prior stores to memory are completed with respect to other
-// processors.
-static inline void
-write_barrier(void)
-{
-  // m68k does not reorder writes. We just need to ensure that gcc also doesn't.
-  __asm__ __volatile__(" " : : : "memory");
-}
 #endif
-- 
1.7.10.4

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."